A field of the invention is electrochemical plating processes. Another field of the invention is semiconductors.
Silicon nanoparticles are an area of intense study. When certain size thresholds are reached, elemental silicon nanoparticles demonstrate properties unlike the properties of bulk or atomic silicon. For example, silicon nanoparticles of xcx9c1 nm diameter have shown stimulated emissions. Unlike bulk Si, an optically inert indirect gap material, xcx9c1 nm diameter particles are extremely active optically, exceeding the activity of fluorescein or coumarine, such that single particles are readily detected and imaged, using two-photon near-infrared femto second excitation. See, e.g., Akcakir et al, Appl. Phys. Lett. 76, p. 1857 (2000); Nayfeh et al., Appl. Phys. Left. 75, p. 4112 (1999). Silicon nanoparticles have been synthesized with Hxe2x80x94 or Oxe2x80x94 or functionalized with Nxe2x80x94, or Cxe2x80x94 linkages.
The present invention is directed to silicon nanoparticle plating. The plating of a uniform layer of silicon nanoparticles on various substrates, including metals and silicon, is provided by the invention. The plating method of the invention allows the physical incorporation of silicon nanoparticles onto important substrates.
According to the invention, silicon nanoparticles are applied to a substrate using an electrochemical plating processes, analogous to metal plating. An electrolysis tank of an aqueous or non-aqueous solution, such as alcohol, ether, or other solvents in which a colloid of particles are dissolved operates at a current flow between the electrodes when power is applied thereto. In applying silicon nanoparticles to silicon substrates, a selective area plating may be accomplished by defining areas of different conductivity on the silicon substrate.
Silicon nanoparticle composite platings and stacked alternating material platings are also possible. The addition of metal ions into the silicon nanoparticle solution produces a composite material plating. Either composite silicon nanoparticle platings or pure silicon nanoparticle platings may be stacked with each other or with conventional metal platings.